CHARACTERIZATION OF THE PHARYNGO-UES CONTRACTILE REFLEX IN HUMANS

Preliminary human studies suggest the presence of an upper esophageal sphincter (UES) contractile reflex triggered by pharyngeal water stimu lation. The purposes of this study were to further characterize this r eflex and determine the threshold volume for its activation. We studie d 10 healthy young volunteers by manometric technique before and after topical pharyngeal anesthesia. UES pressure responses to various volu mes and temperatures of water injected into the pharynx were elucidate d. At a threshold volume, rapid-pulse and slow continuous pharyngeal w ater injection resulted in significant augmentation of UES pressure in all volunteers. Threshold volume for inducing UES contraction average d 0.1 +/- 0.01 mi for rapid-pulse injection and was significantly smal ler than that for slow continuous injection (1.0 +/- 0.2 mi). UES pres sure increase duration averaged 16 +/- 4 s. Augmentation of UES restin g tone by injection of water with three different temperatures was sim ilar. This augmentation was abolished after topical anesthesia. Conclu sions were that stimulation of the human pharynx by injection of minut e amounts of water results in a significant increase in resting UES pr essure: the pharyngo-UES contractile reflex. The magnitude of pressure increase due to activation of this reflex is not volume or temperatur e dependent. Loss of pharyngeal sensation abolishes this reflex.